In the implantation of ions upon a semiconductor substrate, the impinging ions heat the substrate, and this can detrimentally affect the substrate, requiring that it be rejected. For instance, photoresistance materials are often deposited upon a substrate prior to implantation to define a pattern in which the ions are to be implanted. If heated to too high a temperature, such photoresistance materials will be destroyed, and implantation will thereafter occur on unwanted areas of the substrate. Also, above a certain temperature, undesirable diffusion effects can occur in a semiconductor substrate. In each of these instances the substrate may be ruined, but its ruined condition may not be detected, and the defective substrate may be subjected to many more expensive treatment steps, before its defective condition is detected.
While it has long been recognized that the temperature of the substrate is a critical factor in ion implantion, no adequate means for monitoring that temperature, or the temperature-dependent damaged state of the substrate, have been known. One of the difficulties is that during the implantation process the substrate is typically placed on a moving carrier, for instance a rapidly spinning disk, contained in a high vacuum. These circumstances have generally prevented the use of direct contacting devices for monitoring the temperature.